In a process of manufacturing articles such as pharmaceuticals and foods, a chamber such as a freeze-drying chamber may be used (for example, PTLs 1 to 4). The articles are moved by a moving member and conveyed inside and outside the chamber. The chamber may be sterilized to prevent microorganisms such as bacteria from entering the articles. For example, in a freeze-drying chamber, the components in the chamber, a plate on which the articles are disposed, and a pipe for supplying a refrigerant are sterilized with high-pressure steam.